This invention relates to a machining unit to be assembled into a machine tool and capable of easily varying inclination of the machining unit with respect to a horizontal base of the machine tool.
Recently, in a workpiece machining field, cases where several kinds of workpieces should be worked by using a single machine tool are increasing and in these cases it often happens to form bores through the workpieces which are inclined in different directions with respect to the horizontal base of the workpiece. For this purpose, the machining unit mounted on the machine tool has to be inclined every time when different workpieces to be bored are fed so as to align the inclination of the machining unit with a desired inclination of a bore to be worked.
Actually, however, when similar, but not exactly the same, workpieces are to be worked, there are many cases where the center of the bores to be worked is positioned at substantially the same position, but the inclinations thereof are different from each other and the center about which the machining unit is inclined is often positioned near the surface of the workpiece or at the inside thereof. For this reason, it is impossible to provide simple hinge means at the center of the inclination of the unit for changing the inclination thereof and it is obliged to provide an additional circular guide with the same center as that of the inclination center mentioned above, and the machining unit is constructed to be slidable on the circular guide. This not only complicates the machining unit but also increases the size of the machine tool.
Therefore, in these days, the above described method is not widely utilized, and when it is required to form bores having different inclinations for the workpieces, the workpieces are inclined every time when different workpieces are worked or machining units having different inclinations are provided for respective working stations. However, in a case where a plurality of the machining units are to be used for working one workpiece to form bores at several points, it is impossible to incline the workpiece when it is required to change the inclination of only one bore to be worked by one machining unit and the others are not changed. In this case, another one working station is required therefor. This makes complicate and bulky the machining unit, i.e., machine tool.